This invention relates to water treatment devices and, in particular, to devices which reduce the formation of scale, including calcium-containing scale, on pipes, heat exchange surfaces, and the like. As used herein, such devices are referred to as xe2x80x9cdescaling decalcifier devicesxe2x80x9d or simply as xe2x80x9cdecalcifier devices.xe2x80x9d
A variety of devices have been proposed for dealing with the problem of scale formation when mineral-containing water is subjected to a heat cycle, such as in a boiler, heat exchanger, cooling tower, or the like. Many of these devices have employed permanent magnetics mounted on the outside of a pipe which conducts the mineral-containing water. These devices form a fixed magnetic field in the area where they are located. This fixed magnetic field causes calcium to separate from the water to form aragonite crystals. Such crystals typically have a rough surface and thus can mechanically lock together to block narrow passages in the water system.
Italian patent application Serial No. VT 92 A 000.07, filed Jul. 27, 1992, which was laid open for inspection between Jan. 27, 1994 and Feb. 25, 1994, discloses a water treatment system employing a piloted reluctance transformer connected to four coils which are wound around a metal pipe carrying the water which is to be treated. Unlike the devices employing permanent magnets, this device creates a varying magnetic field in the water passing through the pipe which interacts with calcium and other ions so as to reduce the tendency of such ions to precipitate within the system. The effect is most pronounced on calcium ions and, in many cases, can essentially completely prevent precipitation of these ions. This interaction between the varying magnetic field and the ions within the water also kills bacteria and inhibits the growth of algae.
Although the device of the above Italian patent application has been found to work successfully in practice, it has had a limitation in that its operation has been sensitive to the frequency of the supply current applied to the piloted reluctance transformer. In particular, the performance of the device drops off significantly when the frequency deviates from the design frequency by more than about xc2x15 hertz. The design frequency of the device of the Italian patent application was 50 hertz, and thus performance was significantly degraded outside of the range from about 45 hertz to about 55 hertz. In particular, performance was degraded at 60 hertz, the nominal line frequency in the United States and other countries.
In view of the foregoing, it is an object of the present invention to provide an improved water treatment device of the type disclosed in the above Italian application which is insensitive to the frequency of the line current used to power the device. In particular, it is an object of the invention to provide such a device which can work effectively with line currents having frequencies throughout the range from about 30 hertz to about 400 hertz, and, in particular, for a line current having a frequency substantially equal to 60 hertz.
It is a further object of the invention, to provide a water treatment device which is more effective than that disclosed in the above Italian patent application.
To achieve these goals, the invention provides a resonator/transformer combination which creates a time varying magnetic field capable of maintaining mineral ions in solution while at the same time being insensitive to the frequency of the power supplied to the transformer.
The resonator employs a diode and four coils, two of which are wound clockwise and two counterclockwise. The transformer also employs four coils, two of which are primary coils and two are secondary coils. The two primary windings are wound in opposite directions to one another and are connected to subtract their potential differential and the two secondary windings are wound in the same manner but in opposition to the phase of the primary windings. The arrangement of these various components is described below in detail. For ease of reference, the arrangement of the components and, in particular, of the transformer when connected to the resonator, is referred to herein as a xe2x80x9cforced sequential rephasingxe2x80x9d arrangement.